The present invention relates generally to methods and apparatus for firmly packing particles or granules in spaced cavities of an article or articles such as cigarette filter rods being moved along a manufacturing line.
Certain articles of manufacture such as charcoal cigarette filters, individual-size packets of granular food products or condiments, capsuled pharmaceuticals, ammunition and the like may require that cavities be completely filled with particles or granules, with the particles being compacted to a desired density or firmness. Several methods exist for adding particles to empty cavities in an article such as a combined filter rod for a cigarette, or other article or articles having spaced cavities. In a cigarette filter rod, for example, cavities to be filled with particles can be spaced in between other filter components. One method for filling the cavities in a cigarette filter rod with particles includes showering the entire filter rod with the particles to allow the particles to fill the spaced cavities. Another method of filling the cavities with particles includes a lug chain that follows the rod as it travels and deposits particles through the lugs into the cavities. Yet another method of filling the cavities with particles uses a pocketed vacuum wheel. The pocketed wheel is driven in synchronization with the filter rod and has internal vacuum which pulls particles into the pockets. As each pocket reaches a corresponding filter rod cavity, the particles are blown from the wheel pocket into the filter rod cavity. With the methods described above, the particles fill the cavities loosely and can result in a difference in the firmness of the rod when the filter component sections of the rod spaced in between the cavities have a different density than the particle filled cavity sections. The difference in density or firmness of the particle filled cavities can present a quality control problem when a consistent firmness for the entire article having the cavities or a consistent firmness from one particle filled cavity to another within an article is desired.
Embodiments of the invention provide methods and apparatus for firmly packing particles or granules in spaced cavities along an article being moved along a manufacturing line. One or more packing mechanisms can be provided downstream of an initial particle filling station in the direction of movement of an article having cavities to be filled with particles or granules. In an embodiment wherein the article with cavities is a combined cigarette filter rod, examples of packing mechanisms for firmly packing the particles in spaced cavities along the filter rod can include a lugged packing wheel, a smooth packing wheel, and a lugged packing belt.
In the case of a lugged packing wheel or a lugged packing belt, or other device having protruding portions that pack only the particles in the spaced cavities, the lugs or protrusions are spaced at a distance that corresponds to the distance between cavities in the article with particles that need to be packed. The lugs are also moved through rotation of the lugged packing wheel or translation of the lugged packing belt at a speed that is synchronized with the speed of movement of the article having cavities to be packed. The synchronization of movement of the packing instrument with movement of the article having cavities ensures that even packing of the particles or granules in the cavities occurs while avoiding damage to the article.
In the case of a combined filter rod or other article having cavities to be filled with particles, side rails can be provided to conform to at least two sides of the article, thereby preventing undesired deformation of the article during the packing process. The side rails in combination with a support rail underneath the article prevent deformation of the article during the packing process while also allowing free movement of the article along the rail support system. An embodiment of the invention can also include the application of vacuum to the support rail. In the case of a combined cigarette filter rod, the porous paper that forms the wrapper of the filter rod allows the vacuum to pull particles into the spaced cavities, thereby helping the compacting process. In additional embodiments, vibration can also be applied to the filter rod or rod support rail to allow the particles to pack tighter as they are being compacted.